Investigating the effect of Cutoff on the stability of earthen canal side slopes

Fluctuation of water level leads to variation of soil moisture regime around canal and cause destruction of the canal side slopes. In this study, stability of side slope of the earthen canal with two different slopes in presence of water table level was studied by using numerical and physical models. Then cut off is considered as a method for controlling failure. The results showed that the seepage surface and piezometric pressure near the side slope are two important factors in stability of side slope of earthen canals. In order to control the destruction of the earthen canal with steeper slope the sheet pile should be installed below the level of the bottom of the canal, but for milder slope the penetration depth of cut off up to the level of the bottom of the canal is adequate. The results showed that the numerical model had good agreement with experimental results in simulation of total pressure, discharge and phreatic line as the average error in estimating the total flow and pressure in the numerical model in comparison with experimental model were, 5.66% and 2.08%, respectively.